44 PRINCIPAL HOUSEHOLD INSECTS. 



entomologist), differs from it in the important particular that its mouth 

 parts are formed for piercing the skin. It is perhaps second in point 

 of abundance to the house fly in most portions of the Northeastern 

 States. 



A third species, commonly called the cluster fly (I'ollenia rudis), is a 

 very frequent visitant of houses, particularly in the spring and fall. 

 This fly is somewhat larger than the house fly, with a dark-colored, 

 smooth abdomen and a sprinkling of yellowish hair. It is not so active 

 as the house fly, and particularly in the fall is very sluggish. At such 

 times it may be picked up readily, and is very subject to the attacks of 

 a fungus disease which causes it to die upon window panes surrounded 

 by a whitish efflorescence. Occasionally this fly occurs in houses in 

 such numbers as to cause great annoyance, but such occurrences are 

 comx)aratively rare. 



A fourth species is another stable fly known as Gyrtoneura stabiilaiis, 

 and a fifth, rather commoner than the last, is the so-called bluebottle 

 fly (Calliphora erythrocephala). This insect is also called the blowfly 

 or meat fly, and breeds in decaying animal material. Another species, 

 about the size of the bluebottle, which breeds abundantly in cow- 

 dung and is also found in houses, although usually in less numbers 

 than the others, is also commonly called the bluebottle or green-bottle 

 i\y(Luc(lia ccesar). 



There is still another species, smaller than any of those so far men- 

 tioned, which is known to entomologists as Homalomyia canicularis, 

 sometimes called the small house fly. It is distinguished from the 

 ordinary house fly by its paler and more pointed body and conical shape. 

 The male, which is much commoner than the female, has large pale 

 patches at the base of the abdomen, which are translucent. When 

 seen on a window pane the light shines through that part of the body. 

 Xot much complaint would be made of house flies were the true house 

 fly a nonexistent form. Under ordinary circumstances it far outnum- 

 bers all other species in houses. Common and widespread as this 

 species is, there is very general ignorance, as with many other extremely 

 common insects, as to its life history and habits outside of the adult 

 stage. Writing in 1873, Dr. A. S. Packard 1 showed that no one in this 

 country had up to that time investigated its habits, and that even in 

 Europe but little attention had been given to it. He showed that the 

 habits were mentioned in only three works, one of which was published 

 during the present century, with figures so poor and inadequate as to 

 be actually misleading. De Geer (1752) showed that ti.e larva lives in 

 warm and humid dung, but did not say how long it remains in the 

 different stages. Bouche (1834)states that the larva lives in horse and 

 fowl's dung, especially when warm; he did not, however, give the 

 length of the larval state. 



1 On the Transformations of the Common Honse Fly, with Notes on Allied Forms. 

 Proc. Boston Soc. Nat. Hist., Vol. XVI, 1874, p. 136. 



